FOAMED PLASTICS - Insulations having a cellular structure.
FP - Abbreviation for fluorocarbon polymer, modified polytetrafluoroethylene (PTFE). See polytetrafluoroethylene.
FPL - Abbreviation for fire protective power-limited signaling circuit cable.
FPLP - Abbreviation for fire protective power-limited signaling circuit plenum cable.
FPLR - Abbreviation for fire protective power-limited signaling circuit riser cable.
FR-1 - See VW-1.
FREQUENCY - The number of times an alternating current reverses itself in one second. Expressed in Hertz (Hz), which is one cycle per second.
FREQUENCY BAND - A particular range of frequencies that forms part of a larger continuous series of frequencies. The internationally agreed radio
frequency bands are shown below:
| Wavelength |
Band |
Frequency |
|
|
| 1 mm - 1 cm |
extremely
high
frequency
(EHF) |
300 - 30 GHz |
|
|
| 1 cm - 10 cm |
superhigh
frequency
(SHF) |
30 - 3 GHz |
|
|
| 10 cm - 1 m |
ultrahigh
frequency
(UHF) |
3 - 0.3 GHz |
|
|
| 1 m - 10 m |
very high
frequency
(VHF) |
300 - 30 MHz |
|
|
| 10 m - 100 m |
high
frequency
(HF) |
30 - 3 MHz |
|
|
| 100 m - 1,000 m |
medium
frequency
(MF) |
3 - 0.3 MHz |
|
|
| 1 Km - 10 Km |
low
frequency
(LF) |
300 - 30 KHz |
|
|
| 10 Km - 100 Km |
very low
frequency
(VLF) |
30 - 3 KHz |
Microwave frequencies, ranging from VHF to EHF bands are usually subdivided into bands designated by letters. These are not internationally agreed upon but the commonly used subdivisions are shown below:
| Band |
Frequency (GHz) |
Wavelength (cm) |
|
|
|
| P |
0.225 - 0.390 |
133.3 - 76.9 |
| L |
0.390 - 1.550 |
76.9 - 19.3 |
| S |
1.550 - 5.20 |
19.3 - 5.77 |
|
|
|
| X |
5.20 - 10.90 |
5.77 - 2.75 |
| K |
10.90 - 36.00 |
2.75 - 0.834 |
| Q |
36.0 - 46.0 |
0.834 - 0.652 |
|
|
|
| V |
46.0 - 56.0 |
0.652 - 0.536 |
| W |
56.0 - 100.0 |
0.536 - 0.300 |
FREQUENCY MULTIPLEXING - The technique of sharing a transmission channel wherein carrier signals of different frequencies are transmitted simultaneously.
FRHF - Abbreviation for flame-retardant and halogen-free. A sheathing material which is flame-retardant, halogen-free, noncorrosive, low-smoke, and non fire propagating.
FRPE - Fire retardant polyethylene.
ft - Abbreviation for feet.
